284 



are seven distant periodic constrictions, or transverse grooves, which are 

 slightly flexuous and somewhat sigmoidal on the sides, and very little 

 arched on the venter. Between these constrictions there are faint indi- 

 cations of low, rounded ribs, which are obsolete at and near the umbilical 

 margin. The other is an imperfect, but undistorted cast of the interior 

 of the septate portion of the shell and of most of the body chamber, not 

 quite six inches and a quarter in its greatest diameter, and an inch and 

 three quarters in breadth. In other respects the characters of these 

 two specimens are essentially the same. 



Professor Yokoyamo, in his monograph of the fossils of the Japanese 

 Chalk, published at Stuttgart in 1890, claims that the Ammonites plan^datus 

 of StoHczka is not the A. planulatus of Sowerby, but the A. Gaudama of 

 Forbes, and refers both to Desmoceras. He also includes the " Haploceras 

 planulatum " nobis, of page 207 of the third part of this volume, though 

 with a query prefixed, among the synonyms of Desmoceras Gaudama. 

 Dr. Kossmat, on the other hand, (who regards Ammonites plamdatus, 

 Sowerby, as the type of the subgenus Puzozia of the genus Desmoceras^ 

 divides the Ammxinites planulatus of Stoliczka into three species, which 

 he calls Puzozia planulata, Sowerby, var. Odiensis, Kossmat ; P. 

 Gaudama (Forbes) ; and P. crebrisulcata, Kossmat. He states also that 

 "Whiteaves' A. planulatus from Division C (Middle Cretaceous) of the 

 Queen Charlotte Islands, exhibits lesser involution and coarser ribbing 

 (geringere Involution und grobere rippung) " than the typical A. planu- 

 latus of Sowerby. But, unfortunately, Dr. Kossmat has not seen any of 

 the specimens of the supposed A. plamdatus from Cumshewa or Maple 

 Island, or even photographs of them, but only the figure, without any 

 description, of the small and very imperfect specimen on Plate 28, flg. 1, 

 of the third part of the present volume. In the writer's judgment, all 

 these specimens agree fairly well with the descriptions and figures of 

 Desmoceras (Puzozia) planulatum (Sowerby) as recently restricted, and 

 differ from them only, so far as can be observed at present, in being a 

 little more tightly rather than more loosely coiled, and, more particularly, 

 in their much straighter periodic constrictions or arrests of growth. 



Desmoceras (Puzozia) Brewerii. 



Ammonites Breiocrii, Gabb. — 1864. Geol. Surv. Calif., Palaeont., vol. i, p. (52, pL 



10, fig. 7 ; and (1869) vol. n, p. 130, pi. 20, fig. 5. 

 Whiteaves —1876. This voliime, pt. 1, p. 21, pi. 1, figs. 2, 2 a, and 

 3, 3 a. 



A specimen collected at Maud Island by Mr. James Deans in 1898, 

 which is essentially similar to the original of figure 3 on Plate I, of this- 



